UV / moisture dual-curing composite adhesive and preparation method thereof

Abstract

The invention relates to a UV (ultraviolet) / moisture dual-curing composite adhesive and a preparation method thereof. The composite adhesive comprises siloxane modified polyurethane; and the SiO2 nanorods are distributed in the siloxane modified polyurethane. The preparation method comprises the following steps: S10, preparing siloxane modified polyurethane; s20, preparation of a SiO2 nanorod; and S30, preparation of the SiO2 NRs / Si-PUA composite adhesive is carried out. The UV / moisture dual-cured resin has the characteristics of no solvent, environmental protection, high efficiency, energy saving, excellent mechanical properties and the like; the SiO2 nanorods can better reflect ultraviolet light, the propagation path of the ultraviolet light in the adhesive is effectively increased, the UV curing depth and efficiency are increased, and the strength, aging resistance, high temperature resistance and other properties of the material are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to a UV / moisture dual-curing composite adhesive and a preparation method thereof. Background Art

[0002] With the development of modern science and technology, the demand for high-performance and multifunctional adhesives is increasing. Traditional adhesives can no longer meet the performance requirements in some special environments and special substrates. Ultraviolet (UV)-cured adhesives made of pure organic materials have limitations under certain environments. For example, the thermal stability and wear resistance of UV-cured organic materials are not as good as those of inorganic materials. These factors lead to their inability to meet certain applications with specific requirements. Moisture curing is generally a process in which groups such as siloxanes or isocyanates react with water in the air at room temperature to cross-link and polymerize, but moisture curing is relatively slow and generally takes a long time to cure, so it can be combined with auxiliary UV curing to achieve rapid drying.

[0003] As a new type of adhesive, nano-SiO2 / modified polyurethane composite adhesive has attracted wide attention in industrial production and scientific research. Specifically, when nano-SiO2 is used as an inorganic filler for polymer materials, it can improve the strength, aging resistance, high temperature resistance, wear resistance, and corrosion resistance of the original polymer materials, and extend the service life of the polymer materials. Nano-SiO2 has strong reflection and scattering properties under ultraviolet light. Adding a small amount of nano-SiO2 filled photocurable resin will scatter the incident ultraviolet light, thereby greatly improving the photocuring efficiency and photocuring depth. These excellent characteristics make its application in polymer composite materials one of the research hotspots.

[0004] SiO2 nanorods (SiO2 NRs) are a form of nano-SiO2 with unique physical and chemical properties, but they exhibit characteristics that are completely different from other forms of nano-SiO2. They have unique advantages in mechanical properties, surface activity and thermal stability. More importantly, for adhesives that require UV curing, they can better reflect ultraviolet light and effectively increase the propagation path of ultraviolet light in the adhesive, thereby further improving the curing depth and efficiency.

[0005] This application conducts further research in this direction. Summary of the invention

[0006] The present invention provides a UV / moisture dual-curing composite adhesive and a preparation method thereof. Specifically, the present invention is solved by the following technical scheme.

[0007] A UV / moisture dual-curing composite adhesive comprises: siloxane-modified polyurethane; and SiO2 nanorods distributed in the siloxane-modified polyurethane.

[0008] Preferably, the siloxane-modified polyurethane is a polyurethane modified with 3-aminopropyltriethoxysilane.

[0009] Preferably, the length of the SiO2 nanorods is 1.5 μm to 1.9 μm, and the diameter is 200 nm to 250 nm.

[0010] A method for preparing a UV / moisture dual-curing composite adhesive in the present application comprises the following steps: S10: Preparation of siloxane-modified polyurethane: Add polytetramethylene glycol to a reaction container, heat it to 45±2°C, add isophorone diisocyanate and 1,4-diazabicyclo[2.2.2]octane to the reaction container, react to obtain a polyurethane prepolymer; then heat it to 60±2°C, add 3-aminopropyltriethoxysilane to the reaction container for siloxane modification to obtain a partially siloxane-terminated polyurethane; then add hydroxyethyl methacrylate to the reaction container for complete end-capping to obtain a siloxane-modified polyurethane, referred to as Si-PUA; S20: Preparation of SiO2 nanorods: Dissolve polyvinyl pyrrolidone in a solvent, add ethanol, water, sodium citrate, and ammonia water after it is completely dissolved, mix well, then add tetraethyl orthosilicate, react at 18°C~22°C for 8~12 hours, separate the solid phase by centrifugation, wash and dry to obtain SiO2 nanorods, called SiO2 NRs; S30: Preparation of SiO2 NRs / Si-PUA composite adhesive: SiO2 NRs powder is added to Si-PUA and dispersed evenly to obtain the SiO2 NRs / Si-PUA composite adhesive.

[0011] Further, in step S20: the solvent is n-pentanol (C5H 12 O); dissolve ag polyvinyl pyrrolidone in 9a~11a mL of solvent; Add a mL of anhydrous ethanol, 0.28 mL of water, 0.1 mL of 0.18 mol / L sodium citrate, and 0.2 mL of ammonia water; add 0.1 mL of ethyl orthosilicate. The a above represents the same algebra, which generally represents the proportional relationship between the materials.

[0012] Furthermore, in step S20: first add anhydrous ethanol, water, and sodium citrate, mix well, then add ammonia water, and perform ultrasonic treatment for at least 8 minutes; then add tetraethyl orthosilicate.

[0013] Furthermore, in step S20, the step of centrifugal separation of the solid phase is: the mixture solution is centrifuged and washed alternately with water and anhydrous ethanol at 3000 rpm / min for at least 3 times, and then the mixture is centrifuged alternately with water and anhydrous ethanol at 2000 rpm / min for at least 3 times, and finally the precipitate is collected and placed in a 60°C oven for drying for 12 h, and then ground after drying.

[0014] Further, in step S30: (0.09±0.01) cg of SiO2 NRs powder is added to 3 cg of Si-PUA; the SiO2 NRs are evenly dispersed by ultrasonication and stirring, and then placed in a vacuum oven for defoaming. The above c represents the same generation, which generally represents the proportional relationship between the materials.

[0015] Further, in step S10: the weight of the polytetramethylene glycol is 10 bg, the weight of the isophorone diisocyanate is (4±0.02) bg, the weight of the 1,4-diazabicyclo[2.2.2]octane is (0.015±0.002) bg; the weight of the 3-aminopropyltriethoxysilane is (0.977±0.005) bg, and the weight of the hydroxyethyl methacrylate is (1.3±0.01) bg. The above b represents the same algebra, which generally represents the proportional relationship between the materials.

[0016] Furthermore, in step S10: after the end-capping, the reaction progress is detected by hydrochloric acid-di-n-butylamine titration method, and the reaction is stopped when the content of the isocyanate group reaches the theoretical value.

[0017] Compared with the prior art, the present invention has the following beneficial effects: in the present application, the UV / moisture dual-curing resin has the characteristics of being solvent-free, green and environmentally friendly, highly efficient and energy-saving, and having excellent mechanical properties; SiO2 nanorods can better reflect ultraviolet light, effectively increase the propagation path of ultraviolet light in the adhesive, increase the UV curing depth and efficiency, and improve the strength, aging resistance, high temperature resistance and other properties of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the curing process of SiO2 nanoparticles in the polyurethane composite adhesive in the present invention.

[0019] Figure 2 This is the FE-SEM image of SiO2 NRs in the present invention.

[0020] Figure 3 Infrared images of Si-PUA and SiO2 NRs in the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] In the following embodiments, the described embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] The following is a method for preparing a UV / moisture dual-curing composite adhesive in one embodiment of the present application.

[0024] (1) Preparation of modified polyurethane adhesive (Si-PUA): First, 10 g of polytetramethylene ether glycol (PTMEG) was placed in a vacuum oven, vacuum dehydrated at 120 °C, and then transferred to a four-necked flask. After the temperature was raised to 45±2 °C, 4.014 g of isophorone diisocyanate (IPDI) and 0.015 g of 1,4-diazabicyclo[2.2.2]octane (DABCO) were added and the mixture was reacted at a constant temperature for 2 h to obtain a polyurethane prepolymer. Then the temperature was raised to 60±2°C and 0.977 g of 3-aminopropyltriethoxysilane (KH550) was added for siloxane modification. The reaction was kept at a constant temperature for 2 hours, and a partially siloxane-terminated polyurethane was obtained. Finally, 1.301 g of hydroxyethyl methacrylate (HEMA) was added for complete end-capping. After end-capping, the reaction progress was detected by the hydrochloric acid-di-n-butylamine titration method. When the content of isocyanate groups reached the theoretical value, the reaction was stopped, and a siloxane-modified polyurethane (Si-PUA) was obtained.

[0025] (2) Isocyanate content test: Add 5 ml of anhydrous toluene to a conical flask containing 0.5-1.0 g of sample, then add 10 mL of 0.1 mol / L di-n-butylamine-toluene solution, shake well to react, then add 10 mL of isopropanol and a drop of bromophenol blue, and finally titrate with 0.5 mol / L hydrochloric acid. The end point is when the indicator color changes from blue to yellow.

[0026] (3) Preparation of SiO2 nanorods: Dissolve 1 g of polyvinylpyrrolidone (PVP) in 10 mL of n-pentanol (C5H 12O), ultrasonic treatment until PVP is completely dissolved (about 2 h), 1 mL of anhydrous ethanol, 0.28 mL of H2O and 0.1 mL of sodium citrate solution (0.18 mol) are added, mixed evenly, 0.2 mL of ammonia water (NH3·H2O) is added for ultrasonication for 10 min, and then 0.1 mL of tetraethyl orthosilicate (TEOS) is added and mixed evenly. After reacting at a constant temperature of 20 ℃ for 8-12 hours, the mixture solution is centrifuged and washed three times with water and anhydrous ethanol alternately at 3000 rpm / min, and the precipitate is collected. In order to remove the smaller nanorods and improve the dispersibility of SiO2NRs, water and anhydrous ethanol are centrifuged alternately for three times at 2000 rpm / min. Finally, the precipitate is collected and dried in a 60 ℃ oven for 12 h. After drying, it is ground for use.

[0027] (4) Preparation of SiO2 NRs / Si-PUA composite adhesive Weigh 3 g of Si-PUA, add 0.09 g of SiO2 NRs powder, and then ultrasonicate and stir until uniformly dispersed. Then put it into a vacuum oven for defoaming for a period of time to avoid affecting the adhesive performance due to the presence of bubbles in the sample during curing.

[0028] At present, the main methods for the composite of SiO2 / cured composite adhesive nanoparticles are: blending method, in-situ growth method and sol-gel method. In this application, IPDI, PTMEG, HEMA and HMDS are used as raw materials to synthesize UV / moisture dual-curing resin (Si-PUA), SiO2 NRs are synthesized by sol-gel method, and SiO2 NRs / Si-PUA composite adhesive using UV / moisture dual curing is prepared by composite.

[0029] In a specific implementation manner, when the SiO2 NRs content in the composite adhesive is 3%, the tensile shear strength of the composite adhesive reaches a maximum of 3.48 MPa, and the curing depth reaches 7.03 mm. At this content, the transmittance is 68.9%, and the pencil hardness reaches a 6 H rating. The tensile shear strength after heating at 120 ° C for 16 h is 3.15 MPa, and the tensile shear strength loss rate is only 9.48%, showing excellent heat resistance. The curing depth, tensile shear strength, heat resistance, pencil hardness and other related properties of the prepared composite adhesive are improved, and it has a good application prospect.

[0030] See attached figure, Figure 1 The schematic diagram is a principle diagram of the process of UV curing of SiO2 nanoparticles in polyurethane composite adhesive. Nano-SiO2 has strong reflection and scattering properties under ultraviolet light. Figure 1As shown in (a), a small amount of nano-SiO2 filled photocurable resin will scatter the incident ultraviolet light of the resin, thereby improving the photocuring efficiency and photocuring depth. Figure 1 As shown in (b), when the content of nano-SiO2 is too high, there is a certain obstacle to UV curing, so the component ratio in this application can achieve a good effect.

[0031] Figure 2 This is the FE-SEM image of SiO2NRs. From the image, we can see that the average length of the rod-shaped SiO2 synthesized by this technology is 1.7 μm and the diameter is about 225 nm.

[0032] Figure 3 The infrared spectra of Si-PUA and SiO2NRs were measured at room temperature of 23°C and humidity of 35%. The samples were in powder form. -1 The absorption peak at 1718 cm is the stretching vibration peak of the NH group. -1 The characteristic peak of C=O appeared at 2266 cm -1 There is an obvious C=N double bond absorption peak at 1638 cm -1 The stretching vibration peak of the C=C double bond at 1111 cm indicates that the C=C double bond of acrylate was successfully introduced into the polymer, showing the PUA structure. -1 The corresponding peak is the stretching vibration absorption peak of the Si-O bond in siloxane, which indicates the successful introduction of moisture curing groups and the successful synthesis of Si-PUA containing siloxane. -1 The absorption peak at 1050 cm is the stretching vibration absorption peak of the OH group on the surface of SiO2 NRs. -1 The corresponding peak is the antisymmetric stretching vibration absorption peak of Si-O bond, 879 cm -1 is the bending vibration absorption peak of Si-OH, 803 cm -1 is the symmetric stretching vibration absorption peak of Si-O bond, 434 cm -1 The bending vibration absorption peak of Si-O bond appeared at , indicating the successful synthesis of SiO2 NRs.

[0033] The protection scope of the present invention includes but is not limited to the above embodiments. The protection scope of the present invention shall be based on the claims. Any replacement, deformation, and improvement of the technology that can be easily thought of by technicians in this field shall fall within the protection scope of the present invention.

Claims

1. A UV / moisture dual-curing composite adhesive, characterized in that: include: Siloxane modified polyurethane; SiO2 nanorods distributed in the siloxane-modified polyurethane.

2. A UV / moisture dual-curing composite adhesive according to claim 1, characterized in that: The siloxane-modified polyurethane is a polyurethane modified by 3-aminopropyltriethoxysilane.

3. A UV / moisture dual-curing composite adhesive according to claim 2, characterized in that: The length of the SiO2 nanorods is 1.5 μm to 1.9 μm, and the diameter is 200 nm to 250 nm.

4. A method for preparing a UV / moisture dual-curing composite adhesive, characterized in that: The following steps are involved: S10: Preparation of siloxane-modified polyurethane: Add polytetramethylene glycol to a reaction container, heat it to 45±2°C, add isophorone diisocyanate and 1,4-diazabicyclo[2.2.2]octane to the reaction container, react to obtain a polyurethane prepolymer; then heat it to 60±2°C, add 3-aminopropyltriethoxysilane to the reaction container for siloxane modification to obtain a partially siloxane-terminated polyurethane; then add hydroxyethyl methacrylate to the reaction container for complete end-capping to obtain a siloxane-modified polyurethane, referred to as Si-PUA; S20: Preparation of SiO2 nanorods: Dissolve polyvinyl pyrrolidone in a solvent, add ethanol, water, sodium citrate, and ammonia water after it is completely dissolved, mix well, then add tetraethyl orthosilicate, react at 18°C ​​to 22°C for 8 to 12 hours, separate the solid phase by centrifugation, wash and dry, and obtain SiO2 nanorods, called SiO2 NRs; S30: Preparation of SiO2 NRs / Si-PUA composite adhesive: The SiO2 NRs powder is added into Si-PUA and dispersed evenly to obtain the SiO2 NRs / Si-PUA composite adhesive.

5. The method for preparing a UV / moisture dual-curing composite adhesive according to claim 4, characterized in that: In step S20: The solvent is n-pentanol; Dissolve ag polyvinyl pyrrolidone in 9a~11a mL of solvent; Add a mL of anhydrous ethanol, 0.28a mL of water, 0.1a mL of 0.18 mol / L sodium citrate, and 0.2a mL of aqueous ammonia; Add 0.1a mL of ethyl orthosilicate.

6. The method for preparing a UV / moisture dual-curing composite adhesive according to claim 5, characterized in that: In step S20: First add anhydrous ethanol, water, and sodium citrate, mix well, then add ammonia water, and ultrasonicate for at least 8 minutes; then add tetraethyl orthosilicate.

7. The method for preparing a UV / moisture dual-curing composite adhesive according to claim 6, characterized in that: In step S20, the step of centrifugation to separate the solid phase is: The mixture solution was washed by alternating centrifugation with water and anhydrous ethanol at 3000 rpm / min for at least 3 times, and then the precipitate was collected and centrifuged alternately with water and anhydrous ethanol at 2000 rpm / min for at least 3 times. Finally, the precipitate was collected and placed in a 60 °C oven for 12 h, and then ground after drying.

8. The method for preparing a UV / moisture dual-curing composite adhesive according to claim 7, characterized in that: In step S30: (0.09 ± 0.01) cg of SiO2 NRs powder was added to 3 c g of Si-PUA; The SiO2 NRs were uniformly dispersed by ultrasound and stirring, and then placed in a vacuum oven for defoaming.

9. The method for preparing a UV / moisture dual-curing composite adhesive according to claim 8, characterized in that: In step S10: The weight of the polytetramethylene glycol is 10 bg, the weight of the isophorone diisocyanate is (4±0.02) bg, and the weight of the 1,4-diazabicyclo[2.2.2]octane is (0.015±0.002) bg; The weight of the 3-aminopropyltriethoxysilane is (0.977±0.005) bg, and the weight of the hydroxyethyl methacrylate is (1.3±0.01) bg.

10. The method for preparing a UV / moisture dual-curing composite adhesive according to claim 9, characterized in that: In step S10: After the end-capping, the reaction progress is detected by hydrochloric acid-di-n-butylamine titration method, and the reaction is stopped when the content of isocyanate groups reaches the theoretical value.

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